High performance AlSiMgCu casting alloy

Abstract

An aluminum casting alloy has 8.5-9.5 wt. % silicon, 0.5-2.0 wt. % copper (Cu), 0.27-0.53 wt. % magnesium (Mg), wherein the aluminum casting alloy includes copper and magnesium such that 4.7≤(Cu+10Mg)≤5.8, and other elements, the balance being aluminum. Selected elements may be added to the base composition to give resistance to degradation of tensile properties due to exposure to heat. The thermal treatment of the alloy is calculated based upon wt. % composition to solutionize unwanted phases having a negative impact on properties and may include a three level ramp-up and soak to a final temperature followed by cold water quenching and artificial aging.

We claim: 
     
       1. A cast aluminum part made from an aluminum casting alloy consisting of:
 8. 5-9.5 wt. % silicon; 
 1. 35-2.0 wt. % copper (Cu); 
 0. 27-0.445 wt. % magnesium (Mg);
 wherein the aluminum casting alloy includes copper and magnesium such that 4.7≤(Cu+10Mg) ≤5.8; 
 
 0 wt. % zinc; 
 up to 0.01 wt. % silver; 
 up to 1.0 wt. % nickel; 
 up to 1.0 wt. % hafnium; 
 0. 14-0.3 wt. % manganese 
 0.08-0.33 wt. % iron 
 0.05-0.12 wt. % titanium; 
 0. 08-0.19 wt. % zirconium; 
 0. 1-0.14 wt. % vanadium; 
 up to 0.10 wt. % of one or more of strontium, sodium and antimony; 
 other elements being ≤0.04 wt. % each and ≤0.12 wt. % in total; and the balance being aluminum; 
 wherein the cast aluminum part contains spherodized silicon particles; 
 wherein the cast aluminum part contains a sufficient amount of the Cu and the Mg to form Q phase precipitates; 
 wherein the cast aluminum part contains a sufficient amount of the Cu and the Mg such that the cast aluminum part is free of undissolved Q phase constituent particles; 
 wherein the amount of undissolved Q phase constituent particles is determined by using the following test method:
 (a) heating the cast aluminum part to 10° C. below the solidus temperature of the cast aluminum part for at least 2 hours; and 
 (b) using SEM to view the microstructure of the cast aluminum part; 
 
 
       wherein, when cast in the form of an ASTM B108 tensile-bar casting, the aluminum casting alloy realizes:
 (i) an ultimate tensile strength of from 450 to 480 MPa; 
 (ii) a first tensile yield strength of from 360 to 390 MPa; 
 (iii) an elongation of from 5 to 9%; 
 (iv) a quality index of from 560 to 610 MPa; and 
 (v) a second tensile yield strength of from 50.8 to 56.7 MPa; 
 
       wherein properties (i)-(iv) are tested at room temperature and after the ASTM B108 tensile-bar casting has been artificially aged at 155° C. for 15 to 60 hours; and 
       wherein property (v) is tested at 300° C. after the ASTM B108 tensile-bar casting has been exposed to a temperature of 300° C. for 500 hours. 
     
     
       2. The cast aluminum part of  claim 1 , wherein the aluminum casting alloy includes copper and magnesium such that 5.0≤(Cu+10Mg)≤5.5. 
     
     
       3. The cast aluminum part of  claim 1 , wherein the aluminum casting alloy includes copper and magnesium such that 5.1≤(Cu+10Mg)≤5.4. 
     
     
       4. The cast aluminum part of  claim 1 , wherein the aluminum casting alloy includes 0.1-0.12 wt. % titanium. 
     
     
       5. The cast aluminum part of  claim 4 , wherein the aluminum casting alloy includes 0.1-0.12 wt. % vanadium. 
     
     
       6. The cast aluminum part of  claim 4 , wherein the aluminum casting alloy includes 0.11-0.13 wt. % zirconium. 
     
     
       7. The cast aluminum part of  claim 1 , wherein the aluminum casting alloy includes 0 wt. % nickel. 
     
     
       8. The cast aluminum part of  claim 7 , wherein the cast aluminum part is one of an engine block, a cylinder head, and a piston. 
     
     
       9. The cast aluminum part of  claim 1 , wherein the cast aluminum part contains undissolved iron-containing particles. 
     
     
       10. The cast aluminum part of  claim 1 , wherein the aluminum casting alloy includes at least 1.72 wt. % Cu.